People with HPD can likely feel 'love' intensely, at least at first.
What likely feels wrong to you is the extreme emotions. On some level you must know that if you tried to have a committed realtionship with her that she'll grow bored, and that has nothing to do with you so much as it has to do with she seeks emotional thrills (to cover up other feelings).
It's a big emotional thrill being to seduce and fall in love with someone new. The honeymoon phase of a relationship. Clearly you are enjoying this as well, even at the expense of a committed relationship (p.s. not judging you).
Problem for you is, you two are no longer new. At the moment what is likely keeping it alive is that you are not committed to each other, so it remains exciting for her.
Are you going to be okay emotionally when the newness wears off for her and you find it wasn't so much about you, but about the thrill of the seduction, the honey-moon phase for her? Or are you going to feel like you gave up everything for her only to find that she is bored with you too and end up hurt? She probably won't end up hurt. Read these forums. How rare it is for someone with HPD to lament a relationship failure versus how many NONs here are here because they've been hurt due to a failed relationship. She holds all the cards really because what may feel real to you is, to some degree, more like a game to her so she is unlikely to be hurt where you may end up really hurt.